Turbine exhaust cases typically comprise inner and outer annular shrouds structurally interconnected by a plurality of circumferentially spaced-apart airfoils or struts. In use, the airfoils are exposed to the hot core flow leaving the turbine section and are, thus, subject to thermal expansion. Thermal fight or thermal mismatch between the inner and outer shrouds and the airfoils may result in non-negligible stress levels throughout the exhaust case structure. The thermal fight is amplified by the fact that the inner and outer shrouds tend to be cooler than the airfoils since they are somewhat thermally protected by the developed boundary layers and are also typically exposed to cooler external flows (e.g. fan bypass flow).
Over the years various approaches have been developed to reduce the level of stress in turbine exhaust cases. However, there remains room for improvement.